A two-stage oxygen supply strategy for enhanced l-arginine production by Corynebacterium crenatum based on metabolic fluxes analysis

A two-stage oxygen supply strategy for enhanced l-arginine production by Corynebacterium crenatum based on metabolic fluxes analysis

Abstract

In this study, the metabolic flux distribution analysis of a new l-arginine (Arg) overproducing strain, Corynebacterium crenatum, was carried out under various oxygen supply conditions in order to explore the optimized oxygen supply profile. The metabolic flux analysis indicated that a relatively higher l-arginine production could be obtained under high oxygen supply (HOS) condition overall. However, during the late fermentation phases, a much more stable l-arginine production could be rather achieved under medium oxygen supply (MOS) condition. As a result, a two-stage oxygen supply strategy, which maintained HOS condition during early fermentation phase, and then step-wisely reduced agitation to keep a stable, smooth and moderate dissolve oxygen levels (DO) changing profile throughout the production phases, was proposed. With the proposed control strategy, the final l-arginine concentration of the batch fermentation was largely increased and reached to a high level of 36.6 g L−1, which was 16% and 51% higher than those obtained under the HOS and MOS conditions. The two-stage oxygen supply strategy could also accelerate glucose consumption rate and thus shorten fermentation time under the same batch initial fermentation condition. The relevant metabolic flux analysis verified the effectiveness of the proposed control strategy.